* Kits for peripherals usually comes next. Antenna tuners, power meters, etc.
* Kit radios themselves. Usually more complicated than regular kits but the potential for hands-on learning is huge.
* Tweaking and tuning. Like squeezing every ounce of performance out of your code, you can always refine your radio setup to go farther or do more on less power.
* SOTA - Summits On The Air. Assemble a radio setup that's light enough to carry to the top of a mountain then prove that it works by contacting other people with it. Typically this is a small COTS or kit radio running on AA batteries with a homebrew antenna.
* EME - Create a high-gain directional antenna and a high power amplifier. Aim it the moon and see if you can hear yourself.